DMRT3 Gene Variations in Horse Breeds Selected for Gaited Movement – Established Research and Novel Findings.

Horse gait variation is influenced by the DMRT3 gene, which this study investigated by analyzing known and novel genetic variations in different horse breeds with distinct movement styles.

Background and Objective

• The DMRT3 gene, nicknamed the “gait keeper,” is crucial for controlling non-standard horse gaits such as tölt and pace.
• The study’s aim was to examine the frequency of known polymorphisms and discover potential new variants within the second exon of the DMRT3 gene.
• This genetic region is significant because variations here can influence locomotion patterns in horses.

Materials and Methods

• Samples: 244 biological samples (blood or hair) were collected from six horse breeds, categorized as:
  • Gaited breeds: Icelandic Horse, French Trotter
  • Non-gaited breeds: Arabian Horse, Malopolski Horse
  • Pony breeds: Welsh Pony, Shetland Pony
• Genetic Analysis:
  • The second exon of the DMRT3 gene was analyzed using Sanger sequencing, a technique for determining the nucleotide sequence of DNA.
  • Polymorphisms (genetic variants) found were annotated using databases such as Ensembl and NCBI to classify their possible effects.
• Statistical Analysis:
  • Allele frequencies and genotypes were compared across breeds and breeding populations to identify significant differences.
• In Silico Analysis:
  • Potential functional consequences of newly detected variants on the DMRT3 protein structure and function were predicted using computational models.

Key Findings

• Identification of six polymorphisms within the second exon of DMRT3, including three novel variants previously unreported.
• The well-known stop-gain mutation c.902C>A (DMRT3_Ser301STOP), which truncates the protein, was found predominantly in the gaited Icelandic Horses and French Trotters.
• Significant differences in genotype distribution at DMRT3_Ser301STOP were observed between two French Trotter breeding studs, indicating genetic variation within the breed’s subpopulations.
• Novel missense variants such as p.Tyr323Asn (amino acid substitution) and a synonymous change c.855T>C (which does not change amino acid but might affect gene regulation) were found mainly in the non-gaited breeds.
• In silico analyses suggest that none of the newly identified variants drastically alter the predicted tertiary structure or function of the DMRT3 protein, implying subtle or regulatory genetic effects.

Conclusions and Implications

• The study confirms that the DMRT3_Ser301STOP variant is a key genetic marker associated with gaited horse breeds.
• Novel polymorphisms found expand the understanding of genetic diversity in the DMRT3 gene across different horse breeds, suggesting a more complex genetic architecture underlying locomotion traits than previously recognized.
• Variations appear to be breed- and population-specific, which is important for selective breeding programs aiming to enhance or preserve gait qualities in horses.
• The persistence of DMRT3 variants as markers highlights their potential utility in equine genetics research, selective breeding, and possibly understanding locomotor neural circuitry.
• Future research could further explore the functional implications of these new variants and their role in broader locomotive phenotypes beyond traditional gaitedness.

Summary

• This study enriches the current knowledge on how the DMRT3 gene influences horse locomotion by combining traditional genetic sequencing, careful breed comparison, and computational biology tools.
• It provides practical insights relevant for breeders, geneticists, and equestrian communities interested in gait traits and overall horse performance.